libceph: allow ceph_buffer_put() to receive a NULL ceph_buffer

Signed-off-by: Luis Henriques <[e-mail]>
Reviewed-by: Jeff Layton <[e-mail]>
Signed-off-by: Ilya Dryomov <[e-mail]>

include/linux/ceph/buffer.h

···
 
 static inline void ceph_buffer_put(struct ceph_buffer *b)
 {
-	kref_put(&b->kref, ceph_buffer_release);
+	if (b)
+		kref_put(&b->kref, ceph_buffer_release);
 }
 
 extern int ceph_decode_buffer(struct ceph_buffer **b, void **p, void *end);